This case report discusses the reconstruction of an entire thumb metacarpal after a diagnosis of giant cell tumor of bone. The patient underwent excision of the entire thumb metacarpal, followed by interposition of a tricortical iliac crest bone graft and metacarpophalangeal and carpometacarpal joint arthrodeses. This option allowed salvage of the patient's native thumb with functional use as a stable post to which she can pinch and grasp objects. At 9 months postoperatively, there was no evidence of recurrence.